Hi Kjell

We have been doing something similar to what you are trying without having to take the risk of running the DB in Ram, let me explain:

In FB 2.1 64 bits (for Windows) we have been running the superserver version, with a very large DB. We configured the FB server to run about 2 GB of cache in ram, and set many other FB config variables to enhance performance. FB 2.1 64 bits has a limit of how much cache it can hold in ram, I think that is 2.5GB if I remember correctly. The limitation does not make any sense as the OS is 64 Bits and should be able to handle much more (from memory 32 bits OS can handle 2 potency of 32, been 4 GB, and 64 Bit OS would be 2 potency of 64, been a number I cannot even imagine). Any-ways, running the DB in ram is very risky, and you can avoid it by just placing a big cache on the FB configuration, and have a Server with 64 GB ram, and configure the RAID controller to allocate 100% priority to read cache. If you have a good RAID configuration, say 8 HDD on Raid 6, the reading speed would be 6 x HDD speed, and today you can buy SAS HDDs with very fast reading capabilities. I also think you may be able to have the DB file actually cached by the OS (for reading purposes) instead of having FB doing so, then why risk it?

I am not sure if FB 2.1 64 for Linux has the same limitation in terms of the cache, it may be worth checking it,

Cheers,
Fabian

--- In firebird-support@yahoogroups.com, Kjell Rilbe <kjell.rilbe@...> wrote:
>
> Hi,
>
> For performance reasons we're considering a setup where our 50+ Gbyte
> Firebird database would reside on a RAM-disk.
>
> I'd like to hear if anyone else has had experience with running large FB
> databases in RAM. Any problems? Performance compared to disk based? Any
> gotchas?
>
> The server has strong UPS at our hosting company, so we will accept
> nightly backups as "good enough". Backup would be done by bringing the
> system offline and copy the fdb file (currently not using nbackup due to
> an unresolved problem that we suspect was caused by nbackup). backup
> will be made both to local disks and to a remote rsync volume.
>
> The server is a Win 2008 web server, 64 bit.
>
> The current setup is with two RAID 1 volumes, one with OS, app etc, and
> the other with the database file and nothing else. Write cache enabled
> on the disks and forced writes off in the DB.
>
> Thanks,
> Kjell
> --
> ------------------------------
> Kjell Rilbe
> DataDIA AB
> E-post: kjell.rilbe@...
> Telefon: 08-761 06 55
> Mobil: 0733-44 24 64
>
>
> [Non-text portions of this message have been removed]
>